The effect of milk basic protein supplementation on bone metabolism during training of young thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: In laboratory animals, man and cell culture experiments, milk basic protein was reported to suppress bone resorption and promote bone formation. However, no studies in horses have previously examined the effect of milk basic protein. OBJECTIVES: To evaluate the effect of milk basic protein supplementation on bone metabolism in young Thoroughbred horses in training. METHODS: Twenty 2-year-old horses in training were used for 90 days in this study. The treatment group was fed a basal diet with 1 g of milk basic protein and the control group a basal diet only. Blood samples were collected on Days 0, 45 and 90 to determine serum calcium (Ca) and biochemical markers of bone metabolism. Radiographs were taken at the start and end of the study to determine radiographic bone aluminium equivalence (RBAE). RESULTS: Serum osteocalcin (OC) was significantly higher at Day 45 after the beginning of the study in the treatment group compared to that in the control group. The treatment group showed a greater increase in the total RBAE change at the end of this study compared to that in the control group. However, there were no significant differences in serum Ca and carboxy-terminal telopeptide of type I collagen (ICTP) between groups. CONCLUSIONS AND POTENTIAL RELEVANCE: These findings provide preliminary evidence that milk basic protein has an effect on bone formation in 2-year-old Thoroughbred horses in training. However, further studies in larger groups of horses are now required to substantiate our findings.

Application of V200 values for evaluation of training effects in the young thoroughbred under field conditions.

The purpose of this investigation was to study, under field conditions, the usefulness of an incremental exercise test to measure V200 (running velocity [V] at heart rate HR[ of 200 beats/min) for evaluation of training effects in the young Thoroughbred. Five to 112 two-year-old Thoroughbreds were used over 4 years to investigate the correlation between HR and V, the influence of the track and rider's weight to V200, reproducibility of V200 and the changes of V200 as training progresses. The high correlation coefficient between HR and V, and V200 were obtained in horses that exercised smoothly during gait changes and had acceleration during the canter in relaxed and nonexcitable states. The reproducibility of V200 as statistically significant providing the conditions were constant. Furthermore, the regression lines between HR and V gradually declined in parallel as training progressed. The average V200 in 2-year-old Thoroughbreds significantly increased from 623 +/- 55 m/min to 691 +/- 64 m/min after 5 months of training (P < 0.05). We concluded that V200 could easily be measured, that it was useful in evaluating treatment effect and that practical application under field conditions was possible.